# How many calories did I really burn on that run? **URL:** \ **Category:** Factual Questions\ **Created:** [January 20, 2015, 3:27pm UTC](https://boards.straightdope.com/t/how-many-calories-did-i-really-burn-on-that-run/710385 "2015-01-20T15:27:00Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![griffin1977](https://avatars.discourse-cdn.com/v4/letter/g/977dab/32.png) [@griffin1977](https://boards.straightdope.com/u/griffin1977)\ **Post date:** [January 20, 2015, 3:27pm UTC](https://boards.straightdope.com/t/how-many-calories-did-i-really-burn-on-that-run/710385/1 "2015-01-20T15:27:00Z")
It’s pretty common for exercise apps, running machines, etc. to quote a number of calories burned during a work out. How are these numbers calculated? The amount of “useful” work done should be pretty easy to estimate, i.e. you’ve moved a _A_kg body at _B_m/s for _C_s, so you’ve done _X_ calories of work. But as the human body is machine, and its not 100% efficient, you have actually burned far more than _X_ calories, you have burned _eX_ calories where _e_ is the efficiency of your body, as a machine for converting chemical energy into kinetic energy. _e_ seems much harder to estimate sensibly. and seems like it will vary greatly between people (I am sure an Olympic athlete would barely break a sweat on a work out that would half kill me). Is there a some agreed upon estimated value for _e_ everyone uses to give you a “calories burned” number? Do they just assume a value of 1.0 (i.e. your body is perfectly efficient)? Or are there more complicated formula that take into account weight, age, height, heart rate, etc? ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [January 20, 2015, 4:17pm UTC](https://boards.straightdope.com/t/how-many-calories-did-i-really-burn-on-that-run/710385/2 "2015-01-20T16:17:05Z")
Here’s a chart from the Mayo Clinic - [Exercise for weight loss: Calories burned in 1 hour - Mayo Clinic](http://www.mayoclinic.org/healthy-living/weight-loss/in-depth/exercise/art-20050999?pg=2) Your bodyweight is probably the biggest variable in the equation. I’m sure age and body composition also factor in but my uneducated guess is that they’re relatively minor. The references to that chart may have more detailed methodology. ---
**Author:** ![griffin1977](https://avatars.discourse-cdn.com/v4/letter/g/977dab/32.png) [@griffin1977](https://boards.straightdope.com/u/griffin1977)\ **Post date:** [January 20, 2015, 4:25pm UTC](https://boards.straightdope.com/t/how-many-calories-did-i-really-burn-on-that-run/710385/3 "2015-01-20T16:25:39Z")
> [@Telemark](#): > > The references to that chart may have more detailed methodology. Thanks. Its not exactly what I was after. but sounds like [MET](http://en.wikipedia.org/wiki/Metabolic_equivalent) is as close as I am going to get. Don’t exactly see how that maps to mechanical efficency, but I think it must to some degree. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [January 20, 2015, 5:00pm UTC](https://boards.straightdope.com/t/how-many-calories-did-i-really-burn-on-that-run/710385/4 "2015-01-20T17:00:59Z")
The other issue, as explained by \*\*DSeid \*\*here [http://boards.straightdope.com/sdmb/showpost.php?p=18054392&postcount=15](http://boards.straightdope.com/sdmb/showpost.php?p=18054392&postcount=15) is that those estimates are usually what you burned. Not what you burned in excess of what you would have burned sitting in a chair breathing & keeping your body alive but idling. And only that excess represents progress towards a goal of weight loss. Not everybody exercises for the purpose of weight loss, but folks interested in calories usually are. ---
**Author:** ![griffin1977](https://avatars.discourse-cdn.com/v4/letter/g/977dab/32.png) [@griffin1977](https://boards.straightdope.com/u/griffin1977)\ **Post date:** [January 20, 2015, 5:06pm UTC](https://boards.straightdope.com/t/how-many-calories-did-i-really-burn-on-that-run/710385/5 "2015-01-20T17:06:55Z")
> [@LSLGuy](#): > > The other issue, as explained by \*\*DSeid \*\*here [http://boards.straightdope.com/sdmb/showpost.php?p=18054392&postcount=15](http://boards.straightdope.com/sdmb/showpost.php?p=18054392&postcount=15) is that those estimates are usually what you burned. Not what you burned in excess of what you would have burned sitting in a chair breathing & keeping your body alive but idling. > > And only that excess represents progress towards a goal of weight loss. Not everybody exercises for the purpose of weight loss, but folks interested in calories usually are. The MET values I mention above do take that into account (basically MET of 1.0 is basically defined as what an average adult would use sitting on the couch) ---
**Author:** ![griffin1977](https://avatars.discourse-cdn.com/v4/letter/g/977dab/32.png) [@griffin1977](https://boards.straightdope.com/u/griffin1977)\ **Post date:** [January 20, 2015, 5:10pm UTC](https://boards.straightdope.com/t/how-many-calories-did-i-really-burn-on-that-run/710385/6 "2015-01-20T17:10:56Z")
> [@LSLGuy](#): > > Not everybody exercises for the purpose of weight loss, but folks interested in calories usually are. That’s why it seems like an mechanical efficiency value is useful. If you are actually interested in getting from A to B then you want to be efficient. You want as much energy as possible expended doing useful work (as in converted to kinetic energy). If you are just interested in losing weight you want to as inefficient as possible (as you don’t care if the energy is “useful” or not you just want to “use it up”). ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [January 20, 2015, 5:29pm UTC](https://boards.straightdope.com/t/how-many-calories-did-i-really-burn-on-that-run/710385/7 "2015-01-20T17:29:36Z")
> [@griffin1977](#): > > If you are just interested in losing weight you want to as inefficient as possible (as you don’t care if the energy is “useful” or not you just want to “use it up”). Inefficient exercise may not be enjoyable, and you’ll do less of it. If I’m out for a bike ride I’d rather be on an efficient, well tuned bike so I can cover more ground and see more things. That makes my ride more enjoyable and I’m more likely to keep going.